基于关节转角估计器的绳驱动手术微器械位置全闭环控制

手术机器人微器械末端空间狭小，无法安装角度检测传感器，不能进行位置全闭环控制．针对这个问题，提出了一种基于关节转角估计器的闭环控制方法．首先设计了4自由度微器械驱动方案，搭建了手术机器人微器械单关节原理样机实验系统，并基于绳驱动系统的动力学分析设计了关节转角估计器．利用动力学参数辨识的方法给出了关节转角估计器的参数，并通过实验数据分析给出了转角估计器的简化和修正模型．实验结果说明关节转角估计器的输出精度可以达到0.38°．最后以转角估计器的输出值作为反馈信号对微器械关节转角进行了闭环控制实验．结果表明，当系统自由运动时微器械关节转角的最大跟随误差为0.734°；当微器械末端加载1.5N的外力时，关节转角估计器的精度是0.59°，最大跟随误差是1.112°．这些说明本文提出的关节转角闭环控制方法具有比较高的控制精度．

Full Closed-loop Position Control of the Surgical Cable-driven Micromanipulator Based on Joint Angle Estimator

As the micromanipulator of surgical robots works in a narrow space, it is difficult to install any angle sensor at the end, and therefore the closed-loop position control can't be achieved. For this problem, a closed-loop control method based on joint angle estimator is presented. Firstly, a 4-DOF (degree of freedom) driving scheme for micromanipulator is designed, an experiment system is established on the single-joint principle prototype of the surgical robot micromanipulator, and the joint angle estimator is designed based on the dynamics analysis of the cable-driven system. Then, the parameters of joint angle estimator are given through the method of dynamic parameter identification. What's more, the simplified and modified model of the angle estimator is achieved by experimental data analysis. The experiment results show that the output precision of the joint angle estimator can reach 0.38°. Finally, the closed-loop control experiment of the micromanipulator joint angle is carried out by taking the output of the angle estimator as the feedback signal. Results show that the maximum following error of the micromanipulator joint angle is about 0.734° when the system moves freely. The precision of the joint angle estimator is 0.59° and the maximum following error is about 1.112°, when an external force of 1.5N is exerted on the micromanipulator end. These results indicate that the proposed closed-loop joint angle control method has a relatively high control accuracy.